Detectors for use with sheet feeds



'April 20, 1965 J. GAGG 3,179,403

DETECTORS FOR USE WITH SHEET FEEDS Filed Feb. 23, 1962 A'ITORNEY S United States Patent" DETECTORS FOR USE WITH SHEET FEEDS James Gagg, London, England, assignor to Molins Machine Company Limited, London, England, a British company Filed Feb. 23, 1962, Ser. No. 174,937 V Claims priority, application Great Britain, Feb. 24, 1961, 6,879/ 61 3 Claims. (Cl. 271-57) This invention concerns improvements in detectors for use with sheet feeds and provides means whereby the omission to feed a sheet or the feeding of more than one sheet can be detected. Such provision is very important for certain machines for example, packing machines where the sheets constitute blanks for making packets and the absence of a blank might result in waste of materials which the said blank is intended to enclose while on the other hand if more than one blank passes out of the feed the machine may jam or be injured when a plurality of blanks reaches the folding mechanism.

According to the invention there is provided a detector for use with sheet feeding mechanism, comprising a detector position to which sheets are fed, a feeler and means for moving it into and away from said position in timed relationship with the sheet feeding mechanism whereby the presence of a sheet at the detecting position will prevent the feeler moving beyond that position, a switch adapted to be operated by the feeler when the feeler moves beyond said position and means adapted to remove sheets from said position if the sheet feeding mechanism feeds more than one sheet at a time and before the feeler reaches the detecting position, whereby whether the sheet feeding mechanism fails to feed a sheet, or feeds more than one, the switch is operated. The switch may be an ranged to stop the machine.

Further to the invention there is provided a detector for use with sheet feeding mechanism comprising means (e.g., feed rollers) arranged to deliver a sheet to a de-' tecting position, a feeler and means for moving the feeler towards said position at the time a sheet should be at such position, a switch, and a switch operating lever attached to said feeler and adapted to operate the switch if the feeler moves past the position where a sheet should be and a further pair of feeding devices such as rollers beyond the detecting position and spaced apart sufficiently to permit a single sheet to lie between them without being fed further forwards or where more than one sheet has been fed to receive the sheets and feed them forwards thereby removing them from the detecting position so that in either case the feeler operates the switch.

The feeler may be pivoted, and move towards the detecting position when permitted to do so by a cam moving in timed relationship with the sheet feeding apparatus.

Sheets reaching the detecting position in the proper manner may be removed therefrom and carried to the other mechanism which is to handle the sheets by an endless conveyor having pushers attached to it.

An example of the apparatus will now be described with reference to the accompanying drawing which shows sheet feeding apparatus for feeding sheets constituting packet blanks.

Referring to the drawing, blanks are fed from the bottom of a stack 1 by a rotary rubber friction pad 2, fixed to a shaft 3, which feeds the blanks into the nip of rollers 4 and 5 rotating faster than pad 2. When a blank passes out of the nip of rollers 4 and 5 it stops at a detecting position B.

Whilst the blank is at rest a detector finger or feeler 6 is lowered so as to detect the presence of the blank. The finger 6 is loosely pivoted on a spindle 7 and fixed to the finger is a short arm 6A which operates a switch S to stop the machine if a blank is not present in the detecting position.

Fixed to the shaft 7 is an arm 8 which carries a roller 9 at its free end, the' roller riding on a cam 10, fixed to the shaft 3, and kept in contact therewith by a spring 11. Also fixed to the spindle 7 is a lug 12 which acts to lift the finger 6 by contacting a stud 13 fixed to the latter. Thus the finger 6 is raised and permitted to fall at each revolution of the shaft 3.

Positioned just beyond the finger 6 is a pair of rollers 14 and 15, the lower one 15 being driven. The upper roller 14 is carried on an arm 16 of a bell crank lever pivoted at 17. The other arm 18 is urged in a clockwise direction by a spring 19 against a stop 20 which is so adjusted that the rollers 14 and 15 are held apart by a distance equal to 1% times the thickness of the blanks being fed.

In normal running, single blanks are fed by the pad 2 to rollers 4 and 5 which feed each blank in turn to the position shown in the drawing, that is, to the detecting position where the blank is marked B. The blanks wait in this position until lugs 21 on a chain conveyor 22 carry them away to another part of the machine. Whilst the blanks are stationary the finger 6 is lowered, but as its movement is checked by a blank the switch S will not be operated. Due to the gap between rollers 14 and 15 single blanks will not be engaged by them and will remain in the detecting position.

If more than one blank is fed out by the pad 2, rollers 14 and 15 will co-operate to feed the blanks beyond the position B at which single blanks stop. Thus they are removed from the detecting position and there is nothing to impede the downward movement of the finger 6 which passes through a slot in the bed of the apparatus. The arm 6A will be moved to the right far enough to operate the switch S and thus stop the machine. Likewise the machine will be stopped if no blank is fed by the pad 2.

What I claim as my invention and desire to secure by Letters Patent is:

1. In a sheet feeding apparatus for feeding a series of sheets, means for feeding sheets consecutively to a detecting position, means for removing stacked sheets from said detecting position when more than one sheet is simultaneously fed to said po ition, said means for removing stacked sheets comprising a pair of feed rollers positioned beyond said detecting position such that a part of each sheet when located at the detecting position lies between said rollers, said feed rollers being spaced apart more than a single sheet thickness but less than the thickness of two sheets such that said rollers will not engage a single sheet and will engage a stack of two or more sheets to remove them from said detecting position, a feeler for detecting the presence of a sheet at said detecting position, means for moving said feeler in a path through said detecting position and back again in timed relationship with the sheet feeding means, switch means for stopping said sheet feeding apparatus, and means coupled to said feeler to operate said switch upon said feeler moving through said detecting position whereby during operation of said apparatus said feeler will engage each sheet at said detecting position, the feeler stopping short its movement through said detecting position and in the event no sheet is present at said detecting position said feeler will move through said detecting position to operate said switch.

2. Apparatus as claimed in claim 1 wherein said feeler is pivoted and said means for moving said feeler toward and away from said position comprises a cam.

3 Apparatus as claimed in claim 1 WhEEIBil'l'Sflid feed rollers are spaced apart a distance equal to one and one-- half times the thickness of a single sheet.

References Cited by the Examiner UNITED STATES PATENTS 4 765,414 7/04 Dexter 271-56 1,761,607 6/30 Wood 271-56 X 2,479,060 8/49 Davidson 271-56 X VExaminers. 

1. IN A SHEET FEEDING APPARATUS FOR FEEDING A SERIES OF SHEETS, MEANS FOR FEEDING SHEETS CONSECUTIVELY TO A DETECTING POSITION, MEANS FOR REMOVING STACKED SHEETS FROM SAID DETECTING POSITION WHEN MORE THAN ONE SHEET IS SIMULTANEOUSLY FED TO SAID POSITION, SAID MEANS FOR REMOVING STACKED SHEETS COMPRISING A PAIR OF FEED ROLLERS POSITIONED BEYOND SAID DETECTING POSITION SUCH THAT A PART OF EACH SHEET WHEN LOCATED AT THE DETECTING POSITION LIES BETWEEN SAID ROLLERS, SAID FEED ROLLERS BEING SPACED APART MORE THAN A SINGLE SHEET THICKNESS BUT LESS THAN THE THICKNESS OF TWO SHEET SUCH THAT SAID ROLLERS WILL NOT ENGAGE A SINGLE SHEET AND WILL ENGAGE A STACK OF TWO OR MORE SHEETS TO REMOVE THEM FROM SAID DETECTING POSITION, A FEELER FOR DETECTING THE PRESENCE OF A SHEET AT SAID DETECTING POSITION, MEANS FOR MOVING SAID FEELER IN A PATH THROUGH SAID DETECTING POSITION AND BACK AGAIN IN TIMED RELATIONSHIP WITH THE SHEET FEEDING MEANS, SWITCH MEANS FOR STOPPING SAID SHEET FEEDING APPARATUS, AND MEANS COUPLED TO SAID FEELER TO OPERATE SAID SWITCH UPON SAID FEELER MOVING THROUGH SAID DETECTING POSITION WHEREBY DURING OPERATION OF SAID APPARATUS SAID FEELER WILL ENGAGE EACH SHEET AT SAID DETECTING POSITION, THE FEELER STOPPING SHORT ITS MOVEMENT THROUGH SAID DETECTING POSITION AND IN THE EVENT NO SHEET IS PRESENT AT SAID DETECTING POSITION SAID FEELER WILL MOVE THROUGH SAID DETECTING POSITION TO OPERATE SAID SWITCH. 